20.6 Electric Hazards and the Human Body

(a) How much power is dissipated in a short circuit of 220-V AC through a resistance of $0 . \text{250} \Omega$? (b) What current flows?

Find the current through a person and identify the likely effect on her if she touches a 120-V AC source: (a) if she is standing on a rubber mat and offers a total resistance of $\text{300 k} \Omega$; (b) if she is standing barefoot on wet grass and has a resistance of only $\text{4500} \Omega$.

Foolishly trying to fish a burning piece of bread from a toaster with a metal butter knife, a man comes into contact with 120-V AC. He does not even feel it since, luckily, he is wearing rubber-soled shoes. What is the minimum resistance of the path the current follows through the person?

(a) What is the resistance of a 220-V AC short circuit that generates a peak power of 96.8 kW? (b) What would the average power be if the voltage was 120 V AC?

A short circuit in a 120-V appliance cord has a $0 . \text{500} - \Omega$ resistance. Calculate the temperature rise of the 2.00 g of surrounding materials, assuming their specific heat capacity is $0.200 \text{ cal}/\text{g} ⋅º \text{C}$ and that it takes 0.0500 s for a circuit breaker to interrupt the current. Is this likely to be damaging?